[ADF-4444] drag and drop fixes (#4674)

* more granular control over drag and drop

* fix performance, internal drop-zone directive

lib/core/datatable/components/datatable/datatable.component.html

@@ -26,8 +26,7 @@
                  role="columnheader"
                  tabindex="0"
                  title="{{ col.title | translate }}"
-                 (dragover)="onDragOver($event)"
-                 (drop)="onHeaderDrop($event, col)">
+                 adf-drop-zone dropTarget="header" [dropColumn]="col">
                 <span *ngIf="col.srTitle" class="adf-sr-only">{{ col.srTitle | translate }}</span>
                 <span *ngIf="col.title" class="adf-datatable-cell-value">{{ col.title | translate}}</span>
             </div>
@@ -98,8 +97,7 @@
                      (keydown.enter)="onEnterKeyPressed(row, $event)"
                      [adf-context-menu]="getContextMenuActions(row, col)"
                      [adf-context-menu-enabled]="contextMenu"
-                     (dragover)="onDragOver($event)"
-                     (drop)="onCellDrop($event, col, row)">
+                     adf-drop-zone dropTarget="cell" [dropColumn]="col" [dropRow]="row">
                     <div *ngIf="!col.template" class="adf-datatable-cell-container">
                         <ng-container [ngSwitch]="col.type">
                             <div *ngSwitchCase="'image'" class="adf-cell-value">

lib/core/datatable/components/datatable/datatable.component.ts

@@ -701,42 +701,6 @@ export class DataTableComponent implements AfterContentInit, OnChanges, DoCheck,
         const name = this.getNameColumnValue();
         return name ? row.getValue(name.key) : '';
     }
-
-    onDragOver(event: Event) {
-        event.preventDefault();
-    }
-
-    onHeaderDrop(event: Event, column: DataColumn) {
-        event.preventDefault();
-
-        this.elementRef.nativeElement.dispatchEvent(
-            new CustomEvent('header-drop', {
-                detail: {
-                    target: 'header',
-                    event,
-                    column
-                },
-                bubbles: true
-            })
-        );
-    }
-
-    onCellDrop(event: Event, column: DataColumn, row: DataRow) {
-        event.preventDefault();
-
-        this.elementRef.nativeElement.dispatchEvent(
-            new CustomEvent('cell-drop', {
-                detail: {
-                    target: 'cell',
-                    event,
-                    column,
-                    row
-                },
-                bubbles: true
-            })
-        );
-    }
-
 }
 
 export interface DataTableDropEvent {

lib/core/datatable/components/datatable/drop-zone.directive.ts

@@ -0,0 +1,90 @@
+/*!
+ * @license
+ * Copyright 2019 Alfresco Software, Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { Directive, Input, ElementRef, NgZone, OnInit, OnDestroy } from '@angular/core';
+import { DataRow } from '../../data/data-row.model';
+import { DataColumn } from '../../data/data-column.model';
+
+@Directive({
+    selector: '[adf-drop-zone]'
+})
+export class DropZoneDirective implements OnInit, OnDestroy {
+    private element: HTMLElement;
+
+    @Input()
+    dropTarget: 'header' | 'cell' = 'cell';
+
+    @Input()
+    dropRow: DataRow;
+
+    @Input()
+    dropColumn: DataColumn;
+
+    constructor(elementRef: ElementRef, private ngZone: NgZone) {
+        this.element = elementRef.nativeElement;
+    }
+
+    ngOnInit() {
+        this.ngZone.runOutsideAngular(() => {
+            this.element.addEventListener('dragover', this.onDragOver.bind(this));
+            this.element.addEventListener('drop', this.onDrop.bind(this));
+        });
+    }
+
+    ngOnDestroy() {
+        this.element.removeEventListener('dragover', this.onDragOver);
+        this.element.removeEventListener('drop', this.onDrop);
+    }
+
+    onDragOver(event: Event) {
+        const domEvent = new CustomEvent(`${this.dropTarget}-dragover`, {
+            detail: {
+                target: this.dropTarget,
+                event,
+                column: this.dropColumn,
+                row: this.dropRow
+            },
+            bubbles: true
+        });
+
+        this.element.dispatchEvent(domEvent);
+
+        if (domEvent.defaultPrevented) {
+            event.preventDefault();
+            event.stopPropagation();
+        }
+    }
+
+    onDrop(event: Event) {
+        const domEvent = new CustomEvent(`${this.dropTarget}-drop`, {
+            detail: {
+                target: this.dropTarget,
+                event,
+                column: this.dropColumn,
+                row: this.dropRow
+            },
+            bubbles: true
+        });
+
+        this.element.dispatchEvent(domEvent);
+
+        if (domEvent.defaultPrevented) {
+            event.preventDefault();
+            event.stopPropagation();
+        }
+    }
+}